This demographic study seeks to identify and explicate some ways in which employment may affect fertility. It has two specific aims: (1) to provide a detailed analysis of the prevalence and socio-demographic correlates of shift work among dual-earner couples with children; and (2) for women with children under five years of age, to provide an intensive analysis of the relationship between shift work, child care, and fertility. This is a new area of investigation that will be based on two existing data sources: the May 1980 and the June 1982 Current Population Surveys. Preliminary tabulations reveal a high prevalence of shift work among full-time dual-earner couples with children less than 14 years old: A conservative estimate is that one in four such couples includes at least one spouse who works other than a regular day shift. There is a substantial minority of full-time dual-earner couples (over one in ten) for whom there is no overlap at all in the hours each spouse is employed. Occupational and family correlates of such work schedules will be investigated from a "couple" perspective, looking at family size differences. In exploring the relationship between shift work, child care, and fertility, the general thesis is as follows: Among dual-earner couples with children, employment in certain occupations is associated with a high prevalence of parental child care, including father care. This is a consequence of the high prevalence of shift workers in these occupations, many of whom split employment and child care hours with their spouses. Shift work in conjunction with parental child care is associated with (and may be in response to) the unavailability of alternative child care arrangements. Child care constraints on employment, in turn, serve to lower both fertility expectations and fertility behavior. Thus, dual-earner couples with a shift worker will tend to have relatively low fertility. The results of this study should provide not only new knowledge on an important demographic issue, but also a strong rationale for collecting more detailed data on this topic in the future.